1 files changed, 61 insertions, 0 deletions
diff --git a/toolkit/components/osfile/tests/xpcshell/test_telemetry.js b/toolkit/components/osfile/tests/xpcshell/test_telemetry.js
new file mode 100644
index 0000000000..178a27b3d8
--- /dev/null
+++ b/toolkit/components/osfile/tests/xpcshell/test_telemetry.js
@@ -0,0 +1,61 @@
+"use strict";
+
+var {
+  OS: { File, Path, Constants },
+} = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+
+// Ensure that we have a profile but that the OS.File worker is not launched
+add_task(async function init() {
+  do_get_profile();
+  await File.resetWorker();
+});
+
+function getCount(histogram) {
+  if (histogram == null) {
+    return 0;
+  }
+
+  let total = 0;
+  for (let i of Object.values(histogram.values)) {
+    total += i;
+  }
+  return total;
+}
+
+// Ensure that launching the OS.File worker adds data to the relevant
+// histograms
+add_task(async function test_startup() {
+  let LAUNCH = "OSFILE_WORKER_LAUNCH_MS";
+  let READY = "OSFILE_WORKER_READY_MS";
+
+  let before = Services.telemetry.getSnapshotForHistograms("main", false)
+    .parent;
+
+  // Launch the OS.File worker
+  await File.getCurrentDirectory();
+
+  let after = Services.telemetry.getSnapshotForHistograms("main", false).parent;
+
+  info("Ensuring that we have recorded measures for histograms");
+  Assert.equal(getCount(after[LAUNCH]), getCount(before[LAUNCH]) + 1);
+  Assert.equal(getCount(after[READY]), getCount(before[READY]) + 1);
+
+  info("Ensuring that launh <= ready");
+  Assert.ok(after[LAUNCH].sum <= after[READY].sum);
+});
+
+// Ensure that calling writeAtomic adds data to the relevant histograms
+add_task(async function test_writeAtomic() {
+  let LABEL = "OSFILE_WRITEATOMIC_JANK_MS";
+
+  let before = Services.telemetry.getSnapshotForHistograms("main", false)
+    .parent;
+
+  // Perform a write.
+  let path = Path.join(Constants.Path.profileDir, "test_osfile_telemetry.tmp");
+  await File.writeAtomic(path, LABEL, { tmpPath: path + ".tmp" });
+
+  let after = Services.telemetry.getSnapshotForHistograms("main", false).parent;
+
+  Assert.equal(getCount(after[LABEL]), getCount(before[LABEL]) + 1);
+});